In a small Japanese port in the 1960s, things are about to change. Young Umi Matsuzaki, who lives in a house overlooking the sea, faces the longing for her deceased father, who was a sailor. Every day, Umi raises a flag at her home to remember him, but her life takes an unexpected turn when she finds herself drawn to a new student at her school, a young man named Shun Kazama. Shun is passionate and idealistic, with a clear and energetic vision for the future.
As the two young people get to know each other, they find themselves amidst a crisis: the high school they attend is threatened with demolition to make way for a new urban development. Together, they decide to join forces with other students to save their beloved building, the "Old Café," filled with history and memories. Amid conversations about dreams and the depth of their feelings, Umi discovers her own voice and the strength she has to fight for what she loves.
The film weaves an intense story of youthful love with a message about the importance of preserving the past while embracing the future. With the vibrant music and captivating visuals typical of Studio Ghibli, the plot not only explores identity and roots but also reflects the desire to grow and find one's own path in a constantly changing world.